docs: add useful debug CLI

Change-Id: I5ef9ecd741f1623ae1b7a23fa0a4fa6db7e243a3
Signed-off-by: Scott Keeler <skeeler@cisco.com>

docs/reference/cmdreference/trace/index.rst

@@ -0,0 +1,12 @@
+.. _interface:
+
+.. note:: For a complete list of CLI Debug commands refer to the Debug CLI section of the `Source Code Documents <https://docs.fd.io/vpp/18.07/clicmd.html>`_ .
+
+Trace Commands
+===============
+This section identifies the following types of trace commands:
+
+.. toctree::
+   :maxdepth: 2
+
+   trace

docs/reference/cmdreference/trace/trace.rst

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+.. _interface:
+
+.. toctree::
+
+.. note:: For a complete list of CLI Debug commands refer to the Debug CLI section of the `Source Code Documents <https://docs.fd.io/vpp/18.07/clicmd.html>`_ .
+
+
+API Trace
+===========
+
+Summary/Usage
+--------------
+
+api trace [on|off][first <*n*>][last <*n*>][status][free][post-mortem-on][dump|custom-dump|save|replay <*file*>]
+
+Description
+------------
+
+Display, replay, or save a binary API trace.
+
+Declaration and Implementation
+-------------------------------
+
+**Declaration:** api_trace_command (src/vlibmemory/vlib_api_cli.c line 783)
+
+**Implementation:** api_trace_command_fn
+
+Clear Trace
+=============
+
+Summary/Usage
+--------------
+Clear trace buffer and free memory.
+Declaration and implementation
+
+**Declaration:** clear_trace_cli (src/vlib/trace.c line 519)
+
+**Implementation:** cli_clear_trace_buffer
+
+Show Trace
+===========
+
+`Show Trace <../interface/show.html#show-trace>`_
+
+Trace Add
+===========
+
+Summary/Usage
+--------------
+
+Trace given number of packets.
+
+Declaration and Implementation
+-------------------------------
+
+**Declaration:** add_trace_cli (src/vlib/trace.c line 405)
+
+**Implementation:** cli_add_trace_buffer